The Retina

Question 1

Ten Layers of the Retina

Question 2

The retina extends over what portion of the globe?

Answer 2

posterior 2/3 of the globe

Question 3

The retina is internally bound by?

Answer 3

the vitreous body

Question 4

The retina is externally connected to?

Answer 4

Bruch’s membrane

Question 5

When does the retna lose the reddish color and turn gray/opacify?

Answer 5

~ 1 hour after death

Question 6

What detects light and movement in the retina?

Answer 6

Rods

Question 7

What provides color and form vision in the retina?

Answer 7

Cones

Question 8

What is the internal background of the eye?

Answer 8

Fundus Oculi

Question 9

What color is the fundus oculi?

Answer 9

Orange-red color derived from the choroidal blood vessels and the retinal pigment epithelium

Question 10

In fair subjects is the fundus oculi lighter or darker? Darker subjects?

Answer 10

Fair - Lighter fundi

Darker - Darker, grayish fundi

Question 11

When looking at the fundus oculi in albinos what is seen?

Answer 11

White scleral tissue is exposed, one sees choroidal vessels through the retina

Question 12

Where does the optic nerve leave the eye?

Answer 12

At the optic disc or papilla

located 3mm medially to and slightly above the posterior globe

Question 13

What is the optic disc completely devoid of causing the blind spot?

Answer 13

Photoreceptors

Question 14

Where is the fovea centralis located and how big is it?

Answer 14

Temporal to and below the posterior pole

1 - 2 mm in diameter

Question 15

At the fovea centralis retinal (thinning/thickening) produces a _____ _____ in the surface where the nerve elements are heaped to formed _____ ____

Answer 15

Thinning

Shallow Depression

Henle’s Layer

Question 16

How big is the foveola?

Answer 16

0.35 mm in diameter, within the fovea

Question 17

Where are the cones contained?

Answer 17

In the foveola

Question 18

Where is the macula lutea found?

Answer 18

Around the fovea centralis

(yellow spot - yellowish pigment xanthophyll)

Question 19

The ora serrata separates what?

Answer 19

Separates the neural part of the retinal periphery from the ciliary body

Question 20

Where does the ora serrata lie?

Answer 20

8.5 mm behind the limbus

6 mm in front of the equator

Question 21

What are thinner and lighter in the retina (veins/ arteries)?

Answer 21

Arteries

Question 22

Are anastomoses found in the retina?

Answer 22

No

Question 23

Does the fovea contain any vessels?

Answer 23

The fovea is free of obstruction from blood vessels

Question 24

What are the four subdivisions in the retina?

Answer 24

1. Pigment Epithelial Layer
2. Photorecepter Layer
3. The Intermediate Layer
4. The Ganglion Cell Layer

Question 25

What does the the pigment epithelial layer (RPE) form?

Answer 25

Forms a single stratum of epithelial cells attached to Bruch's membrane (There are about 5 million in each eye)

Question 26

Pigmented projections intrude where in the pigment epithelial layer? What do they do?

Answer 26

between adjacent rods and cones Protect receptors from excessive and scattered light

Question 27

Is mitosis demonstrated in the pigment cells?

Answer 27

No

Question 28

Each pigment epithelium cell is in contact with an average of up to how many photoreceptors?

Answer 28

45 photoreceptors

Question 29

What are the functions of the pigment epithelial layer?

Answer 29

FUNCTIONS: 1. Absorption of light and removal of heat 2. Restricts stray light; protects receptors from undesirable effects of light 3. Provides photoreceptors with nutrients/ O2 4. Reservoirs of useful substances (ex. Vit A) 5. Provide slow disintegration, a role in phagocytotic activity

Question 30

Is there a connection between the RPE and receptors? Why?

Answer 30

No anatomical connection exists Leads to the ease with which two layers can be deteched

Question 31

What are photoreceptors?

Answer 31

Sensory cells that transform light into electrical energy by chemical processes

Question 32

What type of arrangement do photoreceptors have?

Answer 32

Palisade arrangment (parallel pickett fence appearance) Held in position by the external limiting membrane

Question 33

What is the size of rods?

Answer 33

Long (40-60 um) Slender (2 um)

Question 34

Where is the photosensitive part of the rods?

Answer 34

The outer segment

Question 35

What is contained in the outer segment?

Answer 35

Rhodopsin (photopigment) 600 - 1000 loosely stacked disc units (lamellae)

Question 36

Lamellae are formed at what rate?

Answer 36

1-5 per hour at the bottom of the segment

Question 37

When do rods slough?

Answer 37

In the morning or in the light after long dark periods (in a group of 30 from top of segment)

Question 38

How long does it take for rod lamellae to be completely renewed?

Answer 38

1-2 weeks